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Publication numberUS3424443 A
Publication typeGrant
Publication dateJan 28, 1969
Filing dateApr 11, 1967
Priority dateApr 11, 1967
Publication numberUS 3424443 A, US 3424443A, US-A-3424443, US3424443 A, US3424443A
InventorsThayer Paul M
Original AssigneeWater Pollution Control Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for diffusing gas into a liquid
US 3424443 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

Jan. 28, 1-969 P. M. THAYEQ I 3,424,443

APPARATUS FOR DIFFUSING GAS INTO A LIQUID Filed April ll, 1967 INVENTOR PAUL M. THAYER AT TORNEY United States Patent 3,424,443 APPARATUS FOR DIFFUSING GAS INTO A LIQUID Paul M. Thayer, Milwaukee, Wis., assignor to Water Pollution Control Corp., Milwaukee, Wis., a corporation of Wisconsin Filed Apr. 11, 1967, Ser. No. 630,129 US. Cl. 261123 2 Claims Int. Cl. Cj 1/08 ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention The present invention'pertains to diffusers adapted to be submerged in a liquid to continuously release gas under pressure, and is more particularly adapted for use as an air diffuser in the aeration tanks of sewage treatment plants.

Description of the prior art The usual air diffuser system in an aeration tank of a sewage treatment plant comprises a difliuser header (one or more) which is disposed in a generally horizontal position and which has a row of openings (on one side or both sides, occasionally along the top or bottom) to which diffusers of various designs may be attached. These prior diffusers are susceptible to easy clogging so that reliable diffusion of air in the proper amounts and proper location is not assured. Clogging may be due to dirty air; to particles entering the passages and small ports from the inside; and may also be due to certain materials in the liquor, such as iron and calcium, which cause deposits to build up at the point of contact between the air and liquor causing external clogging. There are many designs of diffusers, using a wide variety of materials, currently available, all of which are subject to clogging. Also various porous diffuser media have been tried, but such media become internally clogged rather easily because of the minute passageways, and also clog from the outside. When clogging occurs the diffusers must be lifted out and cleaned. This becomes a serious operating problem, especially in the larger plants.

SUMMARY OF THE INVENTION The present invention provides a diffuser which utilizes an open-bottomed chamber adapted to be disposed horizontally in submerged condition, said chamber having an air inlet at one end and having a row of air release ports along each side near the lower edges, air under pressure within the chamber filling the latter above the release ports and somewhat therebelow. Whenever there is a change in the liquor level inside the diffuser this automatically changes the amount of area of the ports which is in communication with the air, thus maintaining a critical velocity through the ports. In this way, even if upper portions of the ports should become clogged, there will be an automatic lowering of the liquid level in the diffuser to open up additional area below the clogged portions. Even if the release ports should become completely clogged, the air pressure would lower the liquid level within the ice diffuser sufficiently to allow release of air from beneath the lower edge of the diffuser. In addition, it is preferred to use a deflector spaced below the diffuser. This causes currents of liquid to flow upwardly along the outer surfaces of the sides of the reservoir to enhance the effectiveness of the release of air from the ports. In this way the diffusion of the proper amount of air is insured at all times.

A general object of the invention, therefore, is to provide a diffuser which is relatively non-clogging, in that air will always be released, and which, therefore, provides for efficient diffusion of the proper amounts of air at all times into the liquor.

A further object of the invention is to provide a diffuser which is so constructed as to maintain the required critical velocity of air through the ports automatically.

A further object of the invention is to provide a diffuser having relatively large release ports, as compared to standard practice, only portions of the large release ports being utilized for the release of air, the remaining area of the ports being available when needed to maintain the critical velocity.

A further object of the invention is to provide in the preferred embodiment, a deflector spaced below the open bottom of the diffuser to provide emergency air release slots between the deflector and the lower edges of the sides, said deflector also causing liquid currents to be directed upwardly along the outer surface of the sides of the diffuser. This aids in shearing off the air bubbles as they emerge from the air release ports, to thus reduce the size of the bubbles and produce small bubble diffusion.

BRIEF DESCRIPTION OF THE DRAWINGS Referring more particularly to the drawings, in which the same reference numerals designate the same parts in all of the views:

FIG. 1 is a side elevational view of a diffuser embodying the features of the present invention, part being broken away and shown in section;

FIG. 2 is a sectional view taken on the line 22 of FIG. 1, the lower arrows indicating the flow of liquid current and the upper arrows indicating the air flow; and

FIG. 3 is a fragmentary vertical sectional view through a sewage tank showing a submerged pair of aerators constructed in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring more particularly to the drawings, the numeral 10 designates a liquid treatment tank which, in the preferred embodiment, is an aeration tank forming part of a sewage treatment plant. An air compressor or pump 11 is adapted to deliver compressed air through conduits 12 and 13 to a vertical pipe 14 having a T-shaped fitting 15 on its lower end, which delivers air through balancing nozzles 17, to distribute the air from the pipe 14 uniformly into the two diffusers 16 which are illustrated. It is to be understood that the feed pipe 14 may feed any desired number of diffusers.

Each diffuser comprises a hoodlike member 18 having an open bottom 19 (see FIG. 2) and having its ends closed by end plates 20 and 21. The nozzle 17 communicates With an opening 22 in the end plate 20.

Each side of the hood portion 18 has a series of air ports 23 arranged in a horizontal line. In a typical embodiment the hood is 2 inches high, and the centers of the ports '23 are located about /2 inch above the lower edge 24 of each side of the hood. The ports are of somewhat larger size than is usual practice for ports of air diffusers, and in the preferred embodiment are inch in diameter.

Suitably supported by the lower portions of the end plates 20 and 21 is a deflector 25 which has its upper portion spaced below the lower edges 24 of the hood portion to provide side air spaces 26 for a purpose to be hereinafter described. In the preferred embodiment the deflector is V-shaped in cross section as is clear from FIG. 2. The spread of the V at its upper portion is such that liquid currents are directed by the deflector in an upward direction to brush past the outer surfaces of the side walls of the hood portion, the deflector preventing the liquid currents from acting within the hood. While the improved invention is advantageous without the deflector 24, nevertheless in the preferred embodiment the use of such deflector is desirable.

Operation In operation, the pump or air compressor 11 is adjusted or sized to deliver a sufiicient volume of air under pressure to the diffuser to meet the particular conditions. The pres sure of the air must be equal to the hydrostatic pressure of the air must be equal to the hydrostatic pressure in the tank in the region of the ports 23, plus an extra increment sufiicient to force the air out through the ports 23, as indicated by the arrows (a), and into the liquor within the tank 10. The air pressure within the hood 18, therefore, lowers the liquid level L within the hood to a level somewhat below the upper portions of the Openings 23. There is always a critical velocity required, depending upon the particular conditions in the tank. This critical velocity is different in different situations. The present invention is adapted to maintain this critical velocity automatically.

In a sewage tank of this type them will be plugging around the edges of the exposed portions of the openings 23 from the inside, due to dirty air. There will also be a buildup of foreign matter, such as iron or calcium, around the exposed portions of the openings, which occurs from the outside. This buildup occurs at the points of contact between water and the air. Such deposits will eventually fill up the upper portions of the openings 23. However, the air within the chamber 26, because its escape is being restricted, will cause a lowering of the liquid level from within the hood 18 to automatically open up sufficient additional area of the openings to maintain the required critical velocity for the particular conditions encountered. Should the ports 23 become completely filled up, after a long period of usage, the liquid level will automatically lower to a point in line with the lower edges 24 of the hood and will allow air to escape around said lower edges 24. Thus the diffuser will always operate to diffuse air into the liquor. This action will take place whether or not the deflector 25 is employed.

When the deflector 25 is used it is spaced below the lower edges 24 to maintain longitudinal air escape slots 27. This deflector also serves a further purpose. In an aeration plant the air is usually introduced along one side by the diffusers. This causes the contents of the tank to move rather rapidly in a circular path, creating currents of liquid which might have an effect in the open bottom 19 of the diffuser. By having a deflector positioned as shown in FIG. 2, the open bottom of the chamber 26 is protected and the currents are caused to flow upwardly along the sides, as indicated by the arrows (b). This action of the liquid currents brushing past the escaping air, indicated by the arrows (a), will shear off the air bubbles and reduce their size, and produce a desirable small bubble type of diffusion. It also creates an agitation which reduces the buildup of foreign matter around the openings.

It is apparent from the above that a very desirable diffuser has been provided which, while applicable to the diffusion of various gases in liquids, is particularly well suited for the diffusion of air into an aeration tank of a sewage treatment plant. It is also apparent that with the use of the present diffusers the amount of time which a diffuser can be operated without cleaning is increased many fold. As a matter of fact, the diffusers could operate indefinitely without cleaning. However, after all of the air ports become completely clogged, it is naturally desirable, when convenient, to open up these air ports.

What I claim is:

1. Sewage treatment apparatus having a liquid tank, having a source of compressed air, and having a conduit connected to said source and extending below the liquid level in the tank, the improvement comprising an openbottomed hood-like diffuser disposed horizontally in said tank and having side walls with lower edges, a connection between an upper portion of said diffuser and said air conduit whereby air under pressure may enter the upper portion of said diffuser to lower the liquid level therein and create an air chamber above said liquid level, each of said side walls having a horizontal series of air release ports in communication with the lower portion of the air chamber, said source of compressed air including means to establish pressure in said chamber sufficiently in excess of the hydrostatic pressure in the region of the release port as to result in discharge of air from upper portions of the ports, and also sufficiently to cause automatic lowering of the liquid level in the diffuser to expose additional release port area as required, and a deflector having opposite upper edges supported in a position to extend in the same direction as and spaced below the lower edges of said side walls of the diffuser and in alignment with said lower edges to create emergency air release space between said lower edges of the diffuser and the opposite edges of the deflector, said deflector having upwardly diverging side walls to direct liquid currents upwardly along the outer surfaces of the side walls of the diffuser past the air release ports to enhance the effectiveness of the latter, said deflector extending the length of the horizontal series of air release ports.

2. Sewage treatment apparatus as claimed in claim 1 in which the deflector is V-shaped in cross-section.

References Cited UNITED STATES PATENTS 1,098,190 5/1914 Stone 26ll24 2,144,385 1/1939 Nordell. 2,986,383 5/1961 Lowry 26 1-124 3,162,702 12/1964 Yonner 210220 X 3,193,260 7/1965 Lamb 21022() X FOREIGN PATENTS 571,970 1/1958 Italy.

RONALD R. WEAVER, Primary Examiner.

US. Cl. X.R.

Patent Citations
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IT571970B * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3802676 *Aug 3, 1971Apr 9, 1974Water Pollution Control CorpMethod for installing aeration systems in sewage treatment tanks
US3915862 *Jun 24, 1974Oct 28, 1975EnvirexSubmerged air release device particularly for sewage treatment
US3926810 *Jun 21, 1974Dec 16, 1975Hoechst AgApparatus for the aeration of effluent with oxygen-containing gas
US3953553 *Feb 28, 1975Apr 27, 1976Water Pollution Control CorporationSewage treatment aeration systems
US4273731 *Oct 26, 1976Jun 16, 1981Laurie Alec HGas/liquid exchange apparatus
US4279842 *Jul 17, 1980Jul 21, 1981Houston Systems Manufacturing Co., Inc.Air diffuser assembly
US4399082 *Jan 27, 1981Aug 16, 1983Kraftwerk Union AktiengesellschaftBlowdown device for steam power plants
US4474714 *Jul 15, 1983Oct 2, 1984Endurex Corp.Diffuser apparatus
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US4759910 *Jan 20, 1987Jul 26, 1988Sulzer Brothers LimitedDistributor for a liquid-liquid extraction or reaction column
US5006283 *Oct 6, 1988Apr 9, 1991General Signal CorporationMixing system for dispersing a compressible fluid such as gas into liquid in a vessel
US5102104 *Mar 5, 1990Apr 7, 1992U.S. Gold CorporationBiological conversion apparatus
US5143543 *Aug 23, 1991Sep 1, 1992U.S. Gold CorporationBiological conversion method
US5376311 *Dec 6, 1993Dec 27, 1994Deguzman; VelApparatus for mixing gas and liquid
US5534202 *Apr 5, 1994Jul 9, 1996Roberts Filter Manufacturing CompanyAir grid for underdrains and similar systems
US5673481 *Apr 10, 1996Oct 7, 1997Rf Delaware, Inc.Air grid for underdrains and similar systems
US7744069 *Jun 15, 2005Jun 29, 2010Invent Umwelt-Und Verfahrenstechnik AgDevice for gassing liquids, in particular waste water
US8132794Nov 28, 2006Mar 13, 2012Air Diffusion SystemsFine bubble delivery for potable water, wastewater, and clean water treatment
US8348247Mar 12, 2012Jan 8, 2013Air Diffusion Systems, A John Hinde CompanyFine bubble delivery for potable water, wastewater, and clean water treatment
US8944421 *Mar 8, 2011Feb 3, 2015Invent Umwelt-Und Verfahrenstechnik AgDevice for aerating a suspension held in a treatment tank
US9061255 *Jul 15, 2011Jun 23, 2015Korea Institute Of Machinery & MaterialsRotating unit-based micro-sized bubble generator
US20080018002 *Jun 15, 2005Jan 24, 2008Marcus HoefkenDevice For Gassing Liquids, In Particular Waste Water
US20080296789 *Nov 28, 2006Dec 4, 2008Air Diffusion SystemsFine Bubble Delivery For Potable Water, Wastewater, And Clean Water Treatment
US20130020728 *Mar 8, 2011Jan 24, 2013Invent Umwelt-Und Verfahrenstechnik AgVertical agitator for wastewater received in a sedimentation tank
US20130113125 *Jul 15, 2011May 9, 2013Korea Institute Of Machinery & MaterialsRotating unit-based micro-sized bubble generator
US20150290563 *Mar 15, 2013Oct 15, 2015General Electric CompanyOpen bottom multiple channel gas delivery device for immersed membranes
CN104780998A *Nov 14, 2012Jul 15, 2015通用电气公司Open bottom multiple channel gas delivery device for immersed membranes
EP0346109A1 *Jun 8, 1989Dec 13, 1989Campbell, Elisabeth MaryDevice for circulation and gas exchange in liquids
WO2014077803A1 *Nov 14, 2012May 22, 2014General Electric CompanyOpen bottom multiple channel gas delivery device for immersed membranes
Classifications
U.S. Classification261/123, 422/255, 261/124, 210/220
International ClassificationC02F3/20, B01F3/04
Cooperative ClassificationB01F2003/04304, C02F3/20, B01F3/04262
European ClassificationB01F3/04C1B2K, C02F3/20
Legal Events
DateCodeEventDescription
Apr 30, 2001ASAssignment
Owner name: SANITAIRE ACQUISITION CORP., DELAWARE
Free format text: CERTIFICATE OF OWNERSHIP AND MERGER;ASSIGNOR:WATER POLLUTION CONTROL CORP.;REEL/FRAME:011511/0897
Effective date: 19860811
Owner name: SANITAIRE ACQUISITION CORP. 229 SOUTH STATE STREET
Free format text: CERTIFICATE OF OWNERSHIP AND MERGER;ASSIGNOR:WATER POLLUTION CONTROL CORP. /AR;REEL/FRAME:011511/0897
Dec 17, 1990ASAssignment
Owner name: WATER POLLUTION CONTROL CORP.
Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:FIRST WISCONSIN NATIONAL BANK OF MILWAUKEE;REEL/FRAME:005612/0020
Effective date: 19901213
Dec 17, 1990AS17Release by secured party
Owner name: FIRST WISCONSIN NATIONAL BANK OF MILWAUKEE
Owner name: WATER POLLUTION CONTROL CORP.
Effective date: 19901213
Sep 11, 1987ASAssignment
Owner name: FIRST WISCONSIN NATIONAL BANK OF MILWAUKEE, 777 EA
Free format text: SECURITY INTEREST;ASSIGNOR:WATER POLLUTION CONTROL CORP. A CORP. OF WI;REEL/FRAME:004757/0741
Effective date: 19870902
Apr 9, 1987ASAssignment
Owner name: WATER POLLUTION CONTROL CORP.
Free format text: MERGER;ASSIGNOR:SANITAIRE ACQUISITION CORP.;REEL/FRAME:004690/0409
Effective date: 19870317
Jan 20, 1987ASAssignment
Owner name: WATER POLLUTION CONTROL CORP., A CORP. OF DE.
Free format text: MERGER;ASSIGNOR:WATER POLLUTION CONTROL CORP., A WI CORP;REEL/FRAME:004652/0469
Effective date: 19860811
Owner name: WATER POLLUTION CONTROL CORP.
Free format text: MERGER;ASSIGNOR:WATER POLLUTION CONTROL CORP., A WI CORP;REEL/FRAME:4652/469
Aug 1, 1986ASAssignment
Owner name: NORWEST BANK ST. PAUL, NATIONAL ASSOCIATION
Free format text: SECURITY INTEREST;ASSIGNOR:WATER POLLUTION CONTROL CORP.;REEL/FRAME:004600/0002
Effective date: 19860730
Owner name: NORWEST BANK ST. PAUL, NATIONAL ASSOCIATION,STATEL
Free format text: SECURITY INTEREST;ASSIGNOR:WATER POLLUTION CONTROL CORP.;US-ASSIGNMENT DATABASE UPDATED:20100524;REEL/FRAME:4600/2
Aug 1, 1986AS06Security interest
Owner name: NORWEST BANK ST. PAUL, NATIONAL ASSOCIATION
Effective date: 19860730
Owner name: WATER POLLUTION CONTROL CORP.